In the production of vehicle internal panelling supports the known wet pressing process has been widely adopted for the production of wood fiber moldings, as disclosed in "Taschenbuch der Spanplattentechnik" by H. J. Deppe, K. Ernst, 2 (1977), p. 252, published by DRW, Leinfelden. Main reasons have been the wide scope of freedom of design, with very deep deformations, and the achievable large size of parts. The last operating step represents a considerable disadvantage: relatively prolonged dry pressing in hot molding tools is required, since the water of the pulp must escape as water vapor through at least one perforated side of the screen, where the image of the screen structure is left on the finished part. No use can be made in the screen zone of pushers or similar ancillary devices such as are required, for example for producing certain edges or undercuttings, and quality-enhancing chemicals or auxiliaries can be added to the vat only to a limited extent, so as not to interfere with the vaporization of the water. Another disadvantage of a technical operating nature is that operations must be performed on "pressing lines", since intermediate storage of the preforms is impossible. Any article therefore always requires heavy use of machinery without guaranteed full utilization.
The first-mentioned disadvantage is avoided when using another process, disclosed in European patent 0 089 013 C2. The dry pressing process discloses therein allows the production on a major manufacturing scale of panelling supports smooth on both sides and the incorporation of pushers or the like in the molding tool. Its disadvantages are that in practice it limits the desirable degree of contour, more particularly as regards the depth of moldings required for modern internal panelling parts, for example, in dashboards or door linings in the motor vehicle industry. Moreover the preforms cannot be transported/stored in an operationally desirable manner.
It is an object of the invention to provide a process of the kind specified which retains all the advantages of the wet pressing process without the disadvantages inherent in the latter or in a dry pressing process, the production of the preforms being disconnected in space and time from the final pressing to produce the support, the result being the creation of new and optimum bases for economic operation.